<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<style>
	
</style>
</head>
<body>

<canvas id="canvas_id" width="200" height="200">
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</canvas>
<script>
	var canvas = {};
	canvas = function(){
		var _pi;
		var _canvas;
		return {
			init : function(){
				_pi = Math.PI;
				_canvas = document.getElementById('canvas_id').getContext('2d');
				this.drawRound();
				this.drawPointer();
			},
			/**
			 * 画刻度
			 */
			drawPointer : function(){
				
			},
			/**
			 * 画圆
			 */
			drawRound : function(){
				_canvas.beginPath();
				_canvas.lineWidth=5;
				_canvas.strokeStyle = '#0000ff';
				_canvas.arc(100,100,96,360,true);
				_canvas.stroke();
				_canvas.closePath();
			}
		}
	}()
	canvas.init();
//	var o = document.getElementById('canvas_id');
//	var ct = o.getContext('2d');
//	ct.beginPath();
//	ct.lineWidth = 5;
//	ct.moveTo(5,5);
//	ct.lineTo(20,40);
//	ct.stroke();
//	ct.closePath();
</script>

</body>
</html>